Field of the Invention
The invention relates to an installation for fabricating semiconductor products. Installations of this type may be designed, in particular, as installations for processing wafers.
These installations include a large number of fabrication units which are used to carry out various fabrication processes for processing the wafers. These fabrication processes are, in particular, etching processes, wet-chemical processes, diffusion processes as well as various cleaning processes, such as for example CMP (chemical-mechanical polishing) processes. One or more fabrication units are provided for each of these fabrication processes.
The entire process of processing the wafers is subject to stringent demands with regard to cleanliness, so that the fabrication units are configured in a clean room or in a system of clean rooms.
The clean room or the system of clean rooms is usually configured on one story of a building.
To supply and discharge operating substances for the individual fabrication units, a supply system is provided.
Operating substances of this type include, in particular, liquid and gaseous operating substances. Liquid operating substances which are required include, in particular, pure water and ultrapure water for a large number of fabrication processes, such as for example cleaning processes, etching and diffusion processes. Furthermore, another liquid operating substance which is required is cooling water to cool machines and installations in the individual fabrication units. Finally, various chemicals in liquid form or in gaseous state are required in order to carry out various fabrication processes.
The supply system has a plurality of reservoirs in which the operating substances which are to be fed to the fabrication units are stored. Moreover, there are a plurality of reservoirs to which operating substances which are removed from the fabrication units are fed.
The reservoirs of the supply system are distributed over one story or several stories of the building which lie below the story on which the clean room is located.
To supply the fabrication units with liquid operating substances, supply lines lead from the corresponding reservoirs to the respective fabrication units. These supply lines lead upward from the reservoirs to the floor of the story of the clean room and, ultimately, open out of the floor in order to be fed to the fabrication units via connections.
A drawback of this configuration is that the liquid operating media have to be pumped upward in the supply lines by means of pumps so that they can be fed to the fabrication units. This on the one hand requires considerable installation costs and on the other hand entails a high energy consumption.
The liquids in the supply lines typically have to overcome height differences of from 2 meters up to 10 meters. To pump up the liquids, the hydrostatic pressure in the supply lines has to be overcome. Moreover, compensating for frictional losses on the inner edges of the supply lines as the liquids flow through require considerable energy.
In some fabrication units, waste air is formed during the processing of the wafers, and this waste air is first contaminated and secondly heated to a greater or lesser extent. This waste air is extracted from the fabrication unit using blowers or the like and is guided, via discharge lines, into a reservoir which is situated on one of the stories which lie below the clean room.
Since the heated waste air rises within the fabrication unit because of convection, considerable energy is required in order to suck the waste air out into the reservoir, which lies below the fabrication unit, via the discharge lines.
It is accordingly an object of the invention to provide an installation for fabricating semiconductor products, in particular, for fabricating wafers, which overcomes the above-mentioned disadvantageous of the prior art apparatus of this general type. In particular, it is an object of the invention to provide a supply system for such an installation, which allows operating substances to be supplied to and discharged from fabrication units of the installation using the minimum possible energy and at the lowest possible cost.
With the foregoing and other objects in view there is provided, in accordance with the invention, an installation for fabricating semiconductor products, that includes: a plurality of fabrication units; at least one clean room in which at least one of the plurality of the fabrication units is configured; and a supply system for supplying and for discharging operating substances for the fabrication units. The supply system includes first supply lines and first discharge lines for downwardly guiding operating substances that are heavier than a surrounding atmosphere. The supply system also includes second supply lines and second discharge lines for upwardly guiding operating substances that are lighter than the surrounding atmosphere.
It should be clear that the installation has a supply system which has first supply and first discharge lines, in which operating substances which are heavier than the surrounding atmosphere are guided from the top downward, and second supply and second discharge lines, in which the lighter operating substances are guided from the bottom upward.
Therefore, in this supply system, operating substances are supplied and discharged using the force of gravity. Operating substances which are heavier than the surrounding atmosphere are guided from the top downward in the first supply lines. In the process, in particular liquid operating substances, such as for example pure water, ultrapure water or cooling water, are fed to the fabrication units from reservoirs which are configured above the corresponding fabrication units. These reservoirs are expediently configured on stories of the building, containing the installation, that lie above the clean room. Accordingly, the first discharge lines lead to reservoirs in stories which lie below the clean room. The liquids are discharged from the fabrication units into these reservoirs.
This method of supplying and discharging entails a minimal outlay on energy. Since the liquids are heavier than the surrounding atmosphere, their own weight assists the flowing movement of the liquids from the top downward in the first supply and discharge lines, so that there is no need to provide any pump systems, or only a few pump systems are required, in order to supply the liquids.
Accordingly, the operating substances which are lighter than the surrounding atmosphere are guided from the bottom upward in the second supply and discharge lines.
By way of example, heated and contaminated waste air is removed upward from the fabrication unit via second discharge lines. This waste air is expediently trapped in reservoirs which are located on stories which lie above the clean room.
Since the heated and contaminated waste air, as a result of convection, flows toward the ceiling of the fabrication unit, the waste air can be extracted from the ceiling out of the fabrication unit and into the discharge lines without great outlay on energy and materials.
In accordance with an added feature of the invention, the operating substances that are supplied by the supply system include liquid chemicals.
In accordance with an additional feature of the invention, the liquid chemicals are etching solutions for carrying out etching processes.
In accordance with another feature of the invention, the etching solutions are selected from the group consisting of KOH and NaOH.
In accordance with a further feature of the invention, the liquid chemicals are selected from the group consisting of alkaline solutions for cleaning wafers and acidic solutions for cleaning wafers.
In accordance with a further added feature of the invention, the operating substances that are supplied by the supply system includes etching gases for carrying out etching processes.
In accordance with a further additional feature of the invention, the etching gases are halogen compounds.
In accordance with a concomitant feature of the invention, the operating substances that are supplied by the supply system include oxygen for cleaning wafers during cleaning processes and nitrogen for drying the wafers.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an installation for processing wafers, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.